[PATCH 0/2] perf trace: Fix support for the new BPF feature in clang 12

[Howard Chu]

The new augmentation feature in perf trace, along with the protocol
change (from payload to payload->value), breaks the clang 12 build.

perf trace actually builds for any clang version newer than clang 16.
However, as pointed out by Namhyung Kim <namhyung@xxxxxxxxxx> and Ian
Rogers <irogers@xxxxxxxxxx>, clang 16, which was released in 2023, is
still too new for most users. Additionally, as James Clark
<james.clark@xxxxxxxxxx> noted, some commonly used distributions do not
yet support clang 16. Therefore, breaking BPF features between clang 12
and clang 15 is not a good approach.

This patch series rewrites the BPF program in a way that allows it to
pass the BPF verifier, even when the BPF bytecode is generated by older
versions of clang.

However, I have only tested it till clang 14, as older versions are not
supported by my distribution.

Howard Chu (2):
  perf build: Change the clang check back to 12.0.1
  perf trace: Rewrite BPF code to pass the verifier

 tools/perf/Makefile.config                    |   4 +-
 .../bpf_skel/augmented_raw_syscalls.bpf.c     | 117 ++++++++++--------
 2 files changed, 65 insertions(+), 56 deletions(-)

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2.43.0